I've thought about adding the Sony RX100 mk4(not sure I need to pay for the mk5). Though I'm not a fan of the menu system, I could get past it. My only gripe is the lack of grip. It's kind of a slippery metal body finish. Adding a strap makes it a pain to put in/take out of the pocket.
I'm most likely going to go 77D route, it's small-ish but has a good grip, has the wheel on the back and a MUCH better AF system than the SL2(though I do LOVE that $550 price), whose size I'd prefer but usability again may make it less used. Not a fan of having to press the AV button and dial instead of just using a wheel, also I like using the wheel to scroll through images, to me its way easier, less hand movements than swiping every single image in play back.
Currently I'm using the original EOS-m(same 18MP sensor as your 60D) w/ the 22f2...it barely fits in my cargo pockets. And the lag while using it is just god awful. The time it takes to actually take the photo, the blackout time afterwards(while it's writing the screen is black and you can't do anything), the time it takes to exit viewing images in playback to get you back to taking a photo... its all just so freaking slow. But I got the pair for $200 on ebay 2 years ago with the purpose of having something on me everywhere. Well it turns out, I don't bring it everywhere. The poor usability takes the fun out of using it. When playing with the M5 at Bestbuy, it seems to have gotten most of that resolved. Though I did see a review of someone mentioning the blackout time still a concern while trying to get action shots of kids. I will be giving my M(1) to my 6yr old soon to get her started. With the press to shutter option on the LCD, its very easy for her to start taking photos.